In the area of usage of super water absorbent compositions, the primary applications have been found in the personal products and water vapor absorption from an environment desired to be kept free of humidity. There are needs to keep certain types of fluids free of water in industrial and fuel dispensing application when water or water vapor invades a liquid.
For instance in the area of under sea seismic oil and gas exploration, the cable containing sensitive electronic equipment is laid in the ocean for days at a time. The cable is joined in 100 meter lengths and is susceptible to sea water invading at the joinder of sections of cable known as the cable connection booted sections or solid body cable connectors or further along the cable if damage occurs. The cables are filled with dielectric oil to protect the equipment. The presence of water causes malfunctioning of geophysical electronic equipment and is a persistent problem in the underwater exploration for oil and gas.
Certain hydrocarbon products are susceptible to the unwanted addition of water which can occur during transportation or storage. Water can become entrapped in barges, train tank cars and barrels diminishing the quality of the hydrocarbon product. In the case of fuels, the presence of water is quite deleterious to engines and very critical for aviation fuel such that special filters have been designed.
Another area of need for water free liquid is in the area of electrical equipment such as transformers which are protected by a tank of dielectric fluid. One method of maintaining the dielectric oil free of water and other contaminants necessitates the installation of a pump and filter system to filter out moisture, particles and the like as shown in U.S. Pat. No. 4,437,082 to Walsh et al. issued on Mar. 13, 1984. Another cartridge filter system is shown in U.S. Pat No. 3,272,742 to Polishuk issued Sept. 13, 1966. The filter systems have the obvious disadvantage of modification of the vessel to accommodate a filter system.
Another approach to absorbing water from a hydrocarbon such as gasoline in a service station storage tank without a filter or cartridge is disclosed in U.S. Pat. No. 3,880,752 to Premo, issued Apr. 29, 1975. The water absorbent polymer is rendered a highly viscous mass capable of absorbing water in the tank, but incapable of being pumped.
Various desiccants have been developed and used for removal of water vapor from ambient air. These packets of desiccants are used in packaging products sensitive to moisture and are shown in Cullen, U.S. Pat. No. 3,990,872 and Deffeyes, U.S. Pat. No. 4,035,360. Desiccant like materials have been packaged in plastic webbing for use in liquids to remove water with a water absorption of 40% by weight in products known as Insulgard and Hydrolock by Diagnetics, Inc. of Tulsa, Oklahoma. This degree of water absorption is magnitudes less than the present invention. The Diagnetics, Inc. products have a water removal quality by squeezing that is not a feature of the present invention which traps the moisture and cannot be squeezed out.
The super water absorbent materials have been developed primarily with the personal products and household emphasis on practical applications. The super absorbent materials have been developed for use in diapers, sanitary napkins, paper towel and wipes. Often these products utilize carboxymethyl cellulose or its derivatives as the water absorbent compound. An example is U.S. Pat. No. 3,589,364 to Dean et al. issued June 29, 1971 which discussed the uses of carboxymethyl cellulose fibers as absorbents for a number of personal products, but also cites a use for a cartridge or cylinder packed with the fibers for absorbing and removing water present in a hydrocarbon fluid by passing the fluid through the cylinder.
Other super water absorbent compounds are disclosed in U.S. Pat. No. 3,661,815 to Smith, issued May 9, 1972, for alkali metal carboxylate salts of starch-polyacrylonitrile graft copolymers with stated utility in the personal and hygiene products area. Another absorbent copolymer which has stated utility for diapers and catamenials is a cross linked sodium polyacrylate disclosed in U.S. Pat. No. 4,295,987 to Parks, issued Oct. 20, 1981.